Vehicle jack



.l. K. BURKHOLDER 1,906,365

VEHICLE JACK Filed may 1a. `192:3

' rfa-z i INVENTOR ATTORNEY Patented May 2, 1933 UNITED STAT-Es PATENT .orticaA JOHN H. BUR-KHOLDER, OF ASHLAND, OHIO, ASSGNOR, BY MESNE ASSIGNMENTS, T ELITE MANUFACTURING- COMPANY, .A CORPOBATIQN 0F OHIO vnHrcLE JACK j Application 'filed May 18, 1328. Serial No. 278,738;

' This invention relates to an improvement in vehicle jacks, and more particularly to a jack ofthe double screw type in which one screw Ineniber telescopes within anotherand a follower device is provided to hold the inner screw member from turning while the outer screw' is being rotated by gearing and a screw-threaded nut.- y In this particular type of jack when both screws are fully exten-ded they are locked together and also locked to the nut so `that should kfurther cranking' or rotative movement occur it is possible to disrupt or work injury tothe follower or holding device. The, object of the present improvement in general is to provide a .Simple mea-ns for safeguarding the operation Aof the follower or holding device, so that no injury or breakage can occur thereto when the double lift screws Vare fully extended and oint rotation thereof is brought about by needless continued rotation ofthe gearing and cranking parts. l

Y- In the accompanyingdrawing, Figl is a sectional View of a double Vscrew jack embodying my invention; Fig. 2`is a'sectional view of the secondary screw,`and Fig. 2al is a cross section thereof on line .2a-2a of Fig. l. Fig. 3 is an enlarged side `view-and sec'- vtion of the followerand holding means,and Fig. ,et a horizontal cross section,on'the same scale as Fig. 3, but taken online Ll-li of Fig. 1. Figs. 5 and 6 are side and sectional views corresponding to Figs. 3 and 4', butshowing a modified forinof the invention. FigL 6 is taken on line 6-6 of Fig. 5. Figs. 7 and 8'v are side and sectional views of a further modification', and Fig. 9 is a sectional view of still another forni of the invention.

The jack comprises a' hollow standardQ having an varched top 3 which is provided with a round opening 4 axially of the standard and throughwhich a pair of hollow telescopic lift members or screwsl 5 and 6, re-v spectively, extend.' A combined gear and nut 7 is rotatably supported upon ball bearing 8 withinarched topf`3r`and a short shaft 9 extends through a, bearing 10 atvoneside of'top 3,'which1shaft carries a vpinion 11 to rotate gear nut 7 Any suitable means such as a rotatable handle or crank (not shown) may beconnected with shaft 9 to crank or rotate'it, as commonly practiced. Nuty 7 `is screw-threaded internally to engage with the threads on screw, which extends downwardly into standard 2 in sliding yengagnnent'with the wall thereof. The upper end of outer scrow is screw-threaded internally tok enn gage the screw-threads on the inner screw 6, which is surinounted byla serrated cap or rest member lafdapted to engage or support the load. VInner screw] 6 is tubularand provided at its bottom with a'square Vopen-v ing to receive a square shaft or follower rod which may be upset or expanded" atl its top to effect uplift of this member when lift screw 6 moves upwardly 'a lpredetermined distance. The lower end offfollower shaft 15 is provided with af holding-device 16 which is constantly heldin slidable Contact orengagement with hollow standard 2; As shown in Figs. 1 toil, standard 2fis formed Vwith a vpairfof longitudinal grooves or channels 174-17 l into which the opposite ends orreduced extensions 18-18 of `holdingV device' 16 proJect. v v This device is-inthe form` of a Hat metal disk or plate 16 having around central open'- ing `18 through which the square rodor shaft` 15 extends. A roundy fla-t disk'l9 is riveted or otherwise aixedgto the bottom end of rod or shaft 15, and a. split spring ring or washer 20 interposedbetween the plate 16 and disk 19. A Cotter pin 21 or other fastening device onfthe rod or shaft holds the plate, split ring and disk in tightfrictional engagement, so thatconsiderable force is required to turn therod or" shaft independently of theplate or holding device 16. A coiled compression spring may be used in lieu of spring washer 20,'b1it'thc latter is preferred. as a more compact assembly of parts can be obtained and the height of the standard reduced accordingly.

lVhen the lift screws are telescoped within each other and the standard the follower device 16 is at rest upon the bottom piece 22 within the standard.

Uplift of the inner screw 6 is produced by rotating the gear and nut, the outer screw 5 rotating with the nut because the friction between this screw and nutis greater than the friction between the two screws 5 and 6, regardless of whether the screws are idling or carrying a load. Theinner screw 6 is prevented from-rotating by the holding device 16. Now assume a loadv is being raised and that the cap at the top of inner screw 6 is engaged with the load. Screw 6 is first to move upwardly (without rotation) and its upward travel within the outer screw 5 is limited or fixed by a pin or stop `element 23 at the bottom or end of the screw thread.

Thus as soon as stop pin 28 reaches the screwthreaded area in the upper part of the outer screw the two screwsv are locked together and further rotation of the gears in the samedirection will cause the nut to drive the outerscrew.-upwardly.- The holding device 16 prevents inner screw 6 from turning and when the two screws are locked together it follows that the outer screw is also prevented from turning by the same device. Accordingly as rotation of the gearing continues the outer screw is raised, carrying the inner screw with it, until the limit of upward travel ofthe. outer screw is reached relatively to nut 7., This limit of travel is established by a pin 24; or other device carried by screw 5 at or near the lower end of its screwthread.A Thus when pin 24 'comes into contact with the bottom of nut 7 the outer screw 5; and the nut are locked together. Consequently a continued rotationk of the gearing would then .not only cause the nut to rotate but it would also cause the outer screw to turn with the nut.- Inasmuch as the inner screw islocked to the outer screw when fully extendedthe force applied to rotate the nut and screws would then be transmit-ted to the square follower shaft or rod and thence to the holding device 16. Now assume the operator is not aware of the critical position of the working parts, and continues to apply power to the j ackmechanism.

Y v The next thing that happens, is that the rod or shaft becomes either badly bent or twisted, or the follower device 16-loosens or breaks, providing the rod or shaft, or the holding device, is not constructed to yield or surrender to such excessive strains.

` The function of the present holder 16 is to grip the rod frictionally or with yielding tension to prevent turning or rotation of the inner screw under normal operating conditioesbst when the screws are fully extended.

and intel-locked with each other and the nut,

the holder 16 yields and relieves the turning stresses or torsion on thc follower shaft and holding device, thereby safeguarding operations and preventing injury or breakage.

The means for holding the inner or secondary screw yieldingly against rotation may be located at either end of the follower rod or shaft, but in Fig. 1, it is shown at the bottom of the shaft and engaged with the walls of the hollow standard or supporting column.

' In Figs. 5 and 6, a modified form of holding device is shown, comprising a dished or flanged plate 25 carrying a pair of bowed wire springs 25vwhich engage' the flat sides of the followerrod or shaft. Normally the shaft and plate are locked together, but under severe torsional stress the square rod or shaft will turn with a snap movement between the pair of wire springs.

In Figs..7 and 8; a pair of spring pressed balls or plungers 26 are mounted within the opposite ends of Va plate or cross bar 27 fixed to the rod or shaft. lhe balls or plungers project into rounded channelsor grooves 28 in the side walls of the standard and the rod or shaft is prevented from turning under normal operating conditions in the jack but surrender underv the more severe stresses when the screws are completely extended and interlocked. I n

In Fig. 9 the square follower rod or shaft 15 is provided with an S-shaped wire spring 29, thercurved spring portions of which bear frictionally against the circular inner' wallof the hollow standard, or within the hollow screw, as maybe elected, to prevent injury or breakage to the working parts when tho screws are fully extended, and a rotative movement is imparted thereto.

What I claim, is: I

1. A vehicle jack, e comprising a hollow standard having guideways;ra pair of lift screws and a rotatable nut mounted upon said standard; means for rotating said nut to elevate said screws; means for interlocking said screws andthe nut when the screws are fully extended; a follower element connected Awith one of said screws; and a holding device engaging said guideways, having frictional rotatable connection with said follower element. a i

2. A vehicle j ack, comprising a vhollow standard; a'rotatable nut mounted upon said standard a pair oftelescopic screws mounted upon said standard and cooperating with said nut; means for rotating said nut; a shaft connected to slide within and rotate withy one screw; a holding .device rotatably connected to said shaft and slidably interlockedwith the wall ofsaid standard; and a friction washer attached to said shaft in frictional contact with saidholding device.

3. A vehicle jack, comprising a standard having guideways, a pair of cooperating telescoping screws within said standard adapted to interlock when extended; means including u rotatable nut mounted upon said Standard adapted to rise and lower said screws. a ollower member slidably connected with one screw, :L rotatable member pivotally connected with said follower member and sldably engaged with the gudeways of said standard, and frietional mea-ns between said follower member and said rotatable member permitting rotation of said follower member and the screws when both screws'are fully extended beyond the standard.

In testimony whereof I aix my signature.

JOHN H. BURKHOLDER. 

